1. Technical Field
This application relates to medical devices, and more particularly, to medical catheters with steering capabilities for use in tracking tortuous pathways or deflecting and/or placing accessories.
2. Background of Related Art
The concept of a variable stiffness microcatheter for use in navigating into tortuous narrow vasculature for delivery of treatment options such as fluid injection or coil placement is disclosed in U.S. Pat. No. 4,739,786, to Engelson. This is achieved by steam shaping the variable stiffness catheter's distal tip and tracking the catheter in combination with a guidewire, straight or curved. While this method allows for quick, accurate access to remote areas such as those in the brain, it does not allow for slight distal tip adjustments to aid in treatment once the destination site is reached. If adjustments are needed, the catheter or the guidewire, or in some instances both, would have to be removed and re-shaped.
U.S. Pat. No. 6,726,700, to Levine, and U.S. Pat. No. 7,591,813, to Levine et al., attempted to correct this shortcoming by disclosing a microcatheter with a deflectable distal tip. Levine describes a co-linear catheter comprising a flexible joint or hinge region defining a main lumen, used for delivery of guidewires and accessories, and a wire lumen that contains a push/pull wire, which is secured to the distal tip with a radiopaque band. Flexion, or bending, of the hinge region is achieved through remote manipulation of the push/pull wire. While this design might work well on a laboratory bench top or in straight vasculature, it fails to consistently deflect in narrow, tortuous anatomy due to its co-linear design featuring the push/pull wire/hinge construction and the inability to introduce fluid into the wire lumen to act as a lubricant to aid in reducing friction between the movable push/pull wire and the wire lumen.
Both of the Levine patents disclose a co-linear, dual lumen (main lumen and wire lumen) deflectable catheter with tip deflection that is brought about through manipulation of a push/pull wire residing in the wire lumen which cannot be lubricated with fluid. Neither of the above mentioned devices disclose a coaxial (inner catheter and outer catheter) device that uses manipulation of the main lumen (inner catheter) and lubrication to bring about smooth, consistent deflection needed to aid in navigation along a small diameter tortuous pathway and to allow for slight tip adjustments to ensure accuracy in delivering fluids and accessories upon arrival at the desired site, as disclosed herein.